Display screen or portion thereof with transitional graphical user interface



FIG. 1 is a first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design in accordance with a first embodiment;

FIG. 2 is a second image thereof;

FIG. 3 is a third image thereof;

FIG. 4 is a fourth image thereof;

FIG. 5 is a first image in a sequence for a display screen or portion thereof with transitional graphical user interface showing our new design in accordance with a second embodiment;

FIG. 6 is a second image thereof;

FIG. 7 is a third image thereof; and,

FIG. 8 is a fourth image thereof.

The appearance of the transitional image sequentially transitions between the images shown in FIGS. 1-4 and FIGS. 5-8. The process or period in which one image transitions to another forms no part of the claimed design. The broken lines around the figures show a display screen or portion thereof and form no part of the claimed design. The broken lines within the figures show portions of the transitional graphical user interface that form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with transitional graphical user interface, as shown and described. 